I've been editing .bashrc files and other init files, and it seems that I've left behind a few code snippets or two that are causing a few errors at the prompt (e.g. file missing), but I can't find them.
How do I debug the prompt to find out what init scripts I've carelessly hacked?
Most of the shells have debug flags that show the commands being executed. Bash may even have one that shows a command before expansion of variables and after. Have you tried checking (I believe) -c -x or -X flags and see if they show the information you are looking for.
You can set them as first thing in the rc files (most global one) or just pass it down into bash command by invoking it from another shell.
In fact, if you invoke bash from another shell, you can also use script command to record everything you see and do into the file, which makes postmortem analysis so much easier.
Try invoking bash with the -x flag, then sourcing your .bashrc or .bash_profile or whatever you're using. That ought to be prolix enough to find your problem
ie:
bash -x
source .bashrc
The easiest way to get a clean initial state is to SSH into your current host, but instead of letting SSH launch your shell with default settings, you provide an explicit command which prevents .bashrc from being read.
ssh -tt localhost /bin/bash --norc
The -tt forces SSH to allocate a TTY, which is what would normally happen when you open a shell connection, but is not default when running an explicit command.
The --norc prevents bash from reading your settings file (since we want to do that ourselves).
You should now be at a bash prompt, in a clean environment. This is useful for examining what variable are set to before your .bashrc runs etc. Enable tracing and source your .bashrc:
set -x # Enable tracing
source .bashrc
Try to see where you've defined prompt - probably it in some dot file in your home directory:
grep PS1 ~/.*
You can see current value of prompt by just printing it:
echo $PS1
HTH
Check the .bash_history file in your home directory to find out what commands you have been running. If you used commands like vi filename to open the init scripts, it will find them in the command history.
Related
Closed. This question is off-topic. It is not currently accepting answers.
Want to improve this question? Update the question so it's on-topic for Stack Overflow.
Closed 10 years ago.
Improve this question
I have a command that runs fine if I ssh to a machine and run it, but fails when I try to run it using a remote ssh command like :
ssh user#IP <command>
Comparing the output of "env" using both methods resutls in different environments. When I manually login to the machine and run env, I get much more environment variables then when I run :
ssh user#IP "env"
Any idea why ?
There are different types of shells. The SSH command execution shell is a non-interactive shell, whereas your normal shell is either a login shell or an interactive shell. Description follows, from man bash:
A login shell is one whose first character of argument
zero is a -, or one started with the --login option.
An interactive shell is one started without non-option
arguments and without the -c option whose standard input
and error are both connected to terminals (as determined
by isatty(3)), or one started with the -i option. PS1 is
set and $- includes i if bash is interactive, allowing a
shell script or a startup file to test this state.
The following paragraphs describe how bash executes its
startup files. If any of the files exist but cannot be
read, bash reports an error. Tildes are expanded in file
names as described below under Tilde Expansion in the
EXPANSION section.
When bash is invoked as an interactive login shell, or as
a non-interactive shell with the --login option, it first
reads and executes commands from the file /etc/profile, if
that file exists. After reading that file, it looks for
~/.bash_profile, ~/.bash_login, and ~/.profile, in that
order, and reads and executes commands from the first one
that exists and is readable. The --noprofile option may
be used when the shell is started to inhibit this behav
ior.
When a login shell exits, bash reads and executes commands
from the file ~/.bash_logout, if it exists.
When an interactive shell that is not a login shell is
started, bash reads and executes commands from ~/.bashrc,
if that file exists. This may be inhibited by using the
--norc option. The --rcfile file option will force bash
to read and execute commands from file instead of
~/.bashrc.
When bash is started non-interactively, to run a shell
script, for example, it looks for the variable BASH_ENV in
the environment, expands its value if it appears there,
and uses the expanded value as the name of a file to read
and execute. Bash behaves as if the following command
were executed:
if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
but the value of the PATH variable is not used to search
for the file name.
How about sourcing the profile before running the command?
ssh user#host "source /etc/profile; /path/script.sh"
You might find it best to change that to ~/.bash_profile, ~/.bashrc, or whatever.
(As here (linuxquestions.org))
Shell environment does not load when running remote ssh command. You can edit ssh environment file:
vi ~/.ssh/environment
Its format is:
VAR1=VALUE1
VAR2=VALUE2
Also, check sshd configuration for PermitUserEnvironment=yes option.
I had similar issue, but in the end I found out that ~/.bashrc was all I needed.
However, in Ubuntu, I had to comment the line that stops processing ~/.bashrc :
#If not running interactively, don't do anything
[ -z "$PS1" ] && return
I found an easy resolution for this issue was to add
source /etc/profile
to the top of the script.sh file I was trying to run on the target system.
On the systems here, this caused the environmental variables which were needed by script.sh to be configured as if running from a login shell.
In one of the prior responses it was suggested that ~/.bashr_profile etc... be used.
I didn't spend much time on this but, the problem with this is if you ssh to a different user on the target system than the shell on the source system from which you log in it appeared to me that this causes the source system user name to be used for the ~.
Just export the environment variables you want above the check for a non-interactive shell in ~/.bashrc.
I was assigned an account for log in to a remote server, and I want to change my default shell.
I tried chsh command but it says: chsh: "/public/home/{my_id}/bin/zsh" is not listed in /etc/shells.
If you don't have permission to install zsh system wide, a quick fix is to append exec ~/bin/zsh -l to ~/.bash_profile (if bash is the current shell), or an equivalent rc file for the current login shell.
zsh -l starts zsh as a login shell.
exec COMMAND replaces the current process with COMMAND, so you'll only have to type exit (or press ctrl+d) once.
~/.bash_profile is executed when bash starts as a login shell, you can still run command bash normally.
Depending what is in ~/.bash_profile (or equivalent), you may wish to avoid executing its other contents, by putting exec ~/bin/zsh -l at the start of the file (not the end), and copy/port anything important over to the zsh equivalent, $ZDOTDIR/.zprofile.
I might also do export SHELL="$HOME/bin/zsh", although I'm unsure of the full effects of setting SHELL differently to that specified for your user in /etc/passwd, to a shell not in /etc/shells, and to a shell binary in your home path.
First check all the shells available on your linux system
cat /etc/shells
Use chsh command line utility for changing a login shell with the -s or –shell option like this.
# chsh --shell /bin/sh tecmint
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
What's the difference between .bashrc, .bash_profile, and .environment?
It seems that if I use
alias ls='ls -F'
inside of .bashrc on Mac OS X, then the newly created shell will not have that alias. I need to type bash again and that alias will be in effect.
And if I log into Linux on the hosting company, the .bashrc file has a comment line that says:
For non-login shell
and the .bash_profile file has a comment that says
for login shell
So where should aliases be written in? How come we separate the login shell and non-login shell?
Some webpage say use .bash_aliases, but it doesn't work on Mac OS X, it seems.
The reason you separate the login and non-login shell is because the .bashrc file is reloaded every time you start a new copy of Bash. The .profile file is loaded only when you either log in or use the appropriate flag to tell Bash to act as a login shell.
Personally,
I put my PATH setup into a .profile file (because I sometimes use other shells);
I put my Bash aliases and functions into my .bashrc file;
I put this
#!/bin/bash
#
# CRM .bash_profile Time-stamp: "2008-12-07 19:42"
#
# echo "Loading ${HOME}/.bash_profile"
source ~/.profile # get my PATH setup
source ~/.bashrc # get my Bash aliases
in my .bash_profile file.
Oh, and the reason you need to type bash again to get the new alias is that Bash loads your .bashrc file when it starts but it doesn't reload it unless you tell it to. You can reload the .bashrc file (and not need a second shell) by typing
source ~/.bashrc
which loads the .bashrc file as if you had typed the commands directly to Bash.
Check out http://mywiki.wooledge.org/DotFiles for an excellent resource on the topic aside from man bash.
Summary:
You only log in once, and that's when ~/.bash_profile or ~/.profile is read and executed. Since everything you run from your login shell inherits the login shell's environment, you should put all your environment variables in there. Like LESS, PATH, MANPATH, LC_*, ... For an example, see: My .profile
Once you log in, you can run several more shells. Imagine logging in, running X, and in X starting a few terminals with bash shells. That means your login shell started X, which inherited your login shell's environment variables, which started your terminals, which started your non-login bash shells. Your environment variables were passed along in the whole chain, so your non-login shells don't need to load them anymore. Non-login shells only execute ~/.bashrc, not /.profile or ~/.bash_profile, for this exact reason, so in there define everything that only applies to bash. That's functions, aliases, bash-only variables like HISTSIZE (this is not an environment variable, don't export it!), shell options with set and shopt, etc. For an example, see: My .bashrc
Now, as part of UNIX peculiarity, a login-shell does NOT execute ~/.bashrc but only ~/.profile or ~/.bash_profile, so you should source that one manually from the latter. You'll see me do that in my ~/.profile too: source ~/.bashrc.
From the bash manpage:
When bash is invoked as an
interactive login shell, or as a
non-interactive shell with the
--login option, it first reads and executes commands from the file
/etc/profile, if that file exists.
After reading that file, it looks for
~/.bash_profile, ~/.bash_login, and
~/.profile, in that order, and reads
and executes commands from the first
one that exists and is readable. The
--noprofile option may be used when the shell is started to inhibit this
behavior.
When a login shell exits, bash
reads and executes commands from the
file ~/.bash_logout, if it exists.
When an interactive shell that is not a login shell is started, bash
reads and executes commands from ~/.bashrc, if that file exists. This
may be inhibited by using the --norc option. The --rcfile file option
will force bash to read and execute commands from file instead of
~/.bashrc.
Thus, if you want to get the same behavior for both login shells and interactive non-login shells, you should put all of your commands in either .bashrc or .bash_profile, and then have the other file source the first one.
.bash_profile is loaded for a "login shell". I am not sure what that would be on OS X, but on Linux that is either X11 or a virtual terminal.
.bashrc is loaded every time you run Bash. That is where you should put stuff you want loaded whenever you open a new Terminal.app window.
I personally put everything in .bashrc so that I don't have to restart the application for changes to take effect.
I could not find the my bash profile which running automatically after login.
I already checked /home/(username) with ls -a.
I am sure there is bash profile because when i echo $somethings, it response.
Could you help me ?
Check for ~/.bash_profile, ~/.bash_login, ~/.profile or even maybe ~/.bashrc, which isn't a "profile", but might be run after login (see INVOCATION in man bash to understand when and in what order bash reads its startup files). If the file doesn't exist, you can create it.
There're also the system-wide /etc/profile and /etc/bash.bashrc.
After /etc/profile, the bash shell (assuming it's either an interactive login shell or run with the --login option) looks for the first file in this set (in your home directory) that exists and is readable:
~/.bash_profile;
~/.bash_login; and
~/.profile.
Hence you may not even have a .bash_profile.
The rules are actually very complex, depending on the type of the shell and the various arguments you give to it. If you want to know in detail, have a look in the INVOCATION section of the bash man page.
If I open a shell into a machine with: putty -load session_name and then execute a command to add a job to a Grid queue on a linux system (qsub -cwd -b hostname), everything works fine.
But if I add the command to a text file, and then do putty -load session_name -m file.txt, I get qsub: command not found
If I back out and simplify the text file to be only the command hostname and use the -m option, it also works fine.
If I use the Connection->SSH->Remote command, and do something similar as the -m command, I get the same results as from the command line.
I'm very much a novice at linux systems, and this seems like it should be a simple fix to tell something that 'qsub' exists somewhere. Either that or there are some restrictions on these remote access things...
Edit:
Ok, so the initial question was how to run it--and I figured that out (add an absolute path), but there are other environment variable issues as well. It appears that qsub requires the SGE_ROOT variable to be set, but that isn't set for the remote commands window either.
So, a better question is, how do I get the putty remote commands shell (using -m) to open with the same properties and setup as a manual command line shell?
qsub is on your path when you log in interactively, but in the non-interactive shell it is not. Give the full path in the script, or set PATH in the script, and you ought to fix your problem.
It seems you need to run your command in the context of an interactive session, but the sshd protocol doesn't directly do that. So try invoking the command indirectly through /bin/sh.
/bin/sh -i -c "qsub -cwd -b hostname"
The -i makes the shell initialize itself like an interactive one, so it will load all the environment variables in your .profile or .bashrc that are loaded in a real interactive shell. The -c provides a command to run within that interactive shell.
You shouldn't have to explicitly set any paths this way since it works in an interactive session.